Malcolm Turnbull has signalled Australia will not seek to withdraw from the Paris climate agreement even if the US president-elect, Donald Trump, follows through on his threat to cancel the emissions reductions commitments made by Barack Obama last December.

Turnbull on Thursday confirmed Australia had ratified the Paris agreement despite domestic opposition from the One Nation party, a critical Senate bloc for the government, and persistent climate change scepticism roiling within Coalition ranks.

After Trump’s victory, and ahead of Turnbull’s confirmation of the government’s intentions with ratification on Thursday morning, the chairman of the government’s backbench committee on the environment and energy, the Liberal MP Craig Kelly said on Facebook the Paris agreement was now “cactus”.

Kelly shared a clip of Trump saying he would cancel the Paris agreement at an oil and gas conference in North Dakota in May.

Turnbull attempted during the session to shrug off Kelly’s display of defiance, declaring he was “proud to enter into agreement on behalf of Australia”.

“My government is committed to [the Paris agreement]. We have ratified it,” he said.

Asked earlier in the day by reporters whether Australia would pull out of the agreement if Trump followed through on his threat to pull out, Turnbull noted the US would not be in a position to do anything quickly.

“If a country sought to withdraw from the agreement it takes four years,” the prime minister told reporters on Thursday.

As for Australia’s position, Turnbull emphasised the fact the Paris agreement was a global undertaking and “when Australia makes a commitment to a global agreement, we follow through, and that is exactly what we are doing”.

The prime minister said the Paris agreement was “a watershed and a turning point” that would deliver international action on climate change.

Australia is the 104th country to ratify the Paris agreement, which came into force earlier this month.

During the routine process of parliamentary review of the agreement, the One Nation senator Malcolm Roberts made a submission arguing the government should not ratify the deal.

Roberts told the joint standing committee on treaties the Paris agreement should not enter into force for Australia “on 4 November 2016 or any other date, until both the science and economics have been rigorously and independently assessed and cause and effect is proven”.

“There is no empirical evidence presented anywhere in the world proving carbon dioxide from human activity affects global climate or evidence that its production needs to be cut,” the One Nation senator said. “On this test alone, the treaty must not be ratified.”

The parliamentary inquiry process produced a raft of submissions from a range of groups making the point Australia would struggle to meet its international climate commitments on current domestic policy settings.

Despite the broad-based criticism, the government has repeatedly declined to say whether a review of the Direct Action policy scheduled for 2017 will yield any significant adjustments to the current policy.

Current indications suggest it will be extremely difficult for the government to increase the current level of policy ambition because of internal resistance within the Coalition – which would create consequential problems given Australia has now signed on to the global emissions reduction framework.

The government’s decision to ratify the Paris agreement was welcomed by a range of environment and community groups on Thursday.

“Ratification of the Paris agreement on climate change is a critical aspect of Australia’s commitment to a long term climate and energy strategy that will help promote community and business confidence,” said the deputy chief executive of the climate institute, Erwin Jackson.

Jackson said the timing of the ratification was also important.

“Given the political events in the USA in the last 24 hours, Australia’s ratification also sends a message to the international community about our national intentions,” he said. “This provides us with a level of credibility to be able to join other nations in encouraging other countries, particularly in our region, to implement the agreement as well.”

Kellie Caught, the Australian spokeswoman for WWF-Australia, said ratification meant the government could now move on to the important task of ensuring Australia had a roadmap to lower emissions in line with our international obligations.

“Australia’s ratification means we can now focus on strengthening policies and actions to achieve the agreement’s goals and objectives – in particular the goal of rapid reductions in emissions,” Caught said.

“WWF believes that the Australian government can and must do more to reduce pollution. The current climate targets and policies are not strong enough to limit global warming to 1.5 degrees and protect the people and places we love.”

Oxfam echoed that sentiment. Its climate change spokesman, Simon Bradshaw, said: “Attention must turn to ramping up the Australian government’s contribution to tackling climate change and bringing it closer into line with what the agreement demands.”

“While ratification is a vital step and should be celebrated, the government is yet to do the math on what the agreement means for Australia and the scale of action we must take if we’re to do our part and help avoid a much more dangerous future.”